 
 (defn string-alpha-numeric-gen
   [rand-seed size]
-  (clojure.string/join (repeatedly size #(call-gen char-alpha-numeric rand-seed size))))
+  (clojure.string/join (repeatedly (call-gen (choose 0 size) rand-seed size)
+                                   #(call-gen char-alpha-numeric rand-seed size))))
 
 (def string-alpha-numeric
   "Generate alpha-numeric strings."


(defn string-gen
  [rand-seed size]
  (clojure.string/join (repeatedly size #(call-gen char rand-seed size))))

(def string
  "Generate strings."

    (let [value (call-gen gen rand-seed size)]
      (if (f value)
        value
        (recur rand-seed (inc size)))))])

;; Generic generators and helpers
;; ---------------------------------------------------------------------------
